Located in the north of the island (not too far from Teror so it's quite possible to do both towns and markets in one day).

An artesean market selling a lot of local produce as well as all the typical stalls you'd expect on a market including some tackey touristy stuff (t-shirts, beach towels, sunglasses....)

San Mateo is a nice town in itself to visit with Canarian arcitecture and the surrounding countryside also enjoyable. 

There's an excursion that visits both Teror and San Mateo markets, you can drive (get directions using the map below) or get the express bus to San Telmo station in Las Palmas and change there for the bus to San Mateo.